Method for custom fitting ski boots

ABSTRACT

Method for custom fitting ski boots by injection comprises injecting a flowable injection material into a suitable cavity in the boot against a predetermined back pressure, suitably created by air or other gas, and maintaining the back pressure during solidification or retention of the fitting material.

o v V 7 United States Patent 11 1 1111 3,876,746 Hanson 1 1 Apr. 8, 1975[54] METHOD FOR CUSTOM FITTING SKI 3.640.003 2/1972 Anderson 36/25 ALBOOTS 3.736.612 6/1973 Check 61.111. 36/2.5 AL V 3,744,159 7/1973Nishimiml 36/25 AL [75] Inventor: Alden W. Hanson,- Migland. Mic3.746.486 7/1973 K6s:e1.,',...- 425/146 [73] Assignee: Hanson Industries1110., Boulder, Colo. Primary Examiner-Robertf. White Assistun!Examiner-T. E; galhoff [22'] 1972 Attorney, Agent, or Firm'Merriam,Marshall, Shapiro [21] Appl. No.1 298,537 & Klosc [52] US. Cl. 264/244;36/25 AL; 264/262; 57 S R CT 264/269; 264/328; 425/129 S; 425/173 15111111. c1 82% 9/10 Method for custom fitting boots by injection [58]Field 61 Search 264/222, 313, 314, 223, p s injecting a flowflbleinjection material into 9 2 4 2 2 2 9 40 323 244; 3 25 suitable cavityin the boot against a predetermined 12/142 P; 425/146 149 129 5 backpressure, suitably created by air or other gas. and maintaining the backpressure during solidification or 15 1 References Ci retention of thefitting material.

, UNITED STATES PATENTS 7 Claims, 2 Drawing Figures 3,632,241 l/l972Vanderhugen et a1 425/146 2/ 22 I 1 I90 23 2e 1 llill ll 1 METHOD FORCUSTOM FITTING SKI BOOTS This invention relates to an improved methodfor custom fitting ski boots by injection. More particularly, theinvention relates to an improved 'pfr'ocess-forcustom fitting ski bootsby the injection of a flowable fitting material into a cavity within theboot under controlled pressure conditions, so as to achieve equaltightness in the individual boots of a pair or, when desired, acontrolled difference in the snugness with which the boots A type of skiboot which is becoming increasingly popular is a shell, typically madeof a substantially rigid synthetic plastic material although otherrelatively resilient materials such as leather can also be used, intowhich is fitted a deformable liner which is intended to conform to theindividual contours of the users foot. The outer shell gives firmsupport to the foot and ankle of the wearer for the purpose of allowinghim to obtain precise and accurate edge control of his skis, while theinner liner is intended to provide a snug and firm yet reasonablycomfortable fit for the wearers foot. The rigidity of the outer shell,however, while contributing markedly to the degree of edge control whichcan be obtained with boots of this type, creates a problem with respectto fitting of the boots. Whereas formerly-used leather boots can usuallystretch somewhat in use to accommodate themselves to the wearers feet,outer shells made of rigid plastic materials are unyielding, andtherefore the only control which can be used for proper fitting is thesize, shape, and resiliency of the liners.

The problem involved in fitting plastic boots is twofold. On the onehand, the wearers foot must be held snugly and firmly within the boot inorder to permit the desired degree of edge control, yet at the same timecalized pressure areas against the wearers foot must be eliminated inorder to provide a reasonable degree of comfort. The fact that skiersfeet may vary widely in contour, even when of the same nominal size,creates a problem in fitting such boots using liners in a few stocksizes.

One of the solutions to the problem of custom fitting rigid plasticbootshas been to provide the liner of the boot with one or more cavities intowhich there is injected a flowable material while the boots are beingworn by the ultimate user. The flowable material adapts the linerprecisely to the contours of the wearers foot and when solidified orotherwise retained in the cavity produces a snug and firm yetcomfortable custom fit.

The flowable materials used to adapt the outer shell of the boot to thewearers foot can be, for example, those described in A. W. Hansons US.Pat. Nos. 3,237,319 and 3,402,41 1 or in the pending application of A.B. Hanson et al., Ser. No. 216,080, filed Jan. 7,

1972. These materials can be wax; foamed-in-place materials such aspolyurethanes; liquids such as mixtures of ethylene glycol orpolyethylene glycol with water; air; partially gelled hydrocarbonmaterials; thickened aqueous or hydrocarbon materials; and the like. Insome instances it may be desirable to use combinations of thesematerials, and in addition, heating of some of the materials to obtainappropriate flowability properties may be desirable or necessary.

Custom fitting of ski boots by the injection ofa flowable fittingmaterial, however, presents the problem that the person being fitted iscalled on to judge subjectively the tightness of fit,- especially theequality of tightness in each boot of a pair. The method of theinvention removes a great deal of the uncertainty involved in customfitting ski boots by injection, and permits equal tightness in bothboots of a pair to be readily obtained. In addition, the method permitsthe fitter to achieve a proper fit for a beginning skier who may have noknowledge of how tight properly fitting boots should feel.

In accordance with the method of the invention, the flowable materialused in fitting is injected into the boot under conditions of controlledpredetermined back pressure, which is maintained while the flowablematerial solidifies, or until the inner liner is sealed to enclose thematerial, whereby there is produced as desired a controllable anduniform degree of tightness in each boot of a pair, or greater tightnessin one boot as desired or necessary to meet special conditions.

The invention will be better understood from the following detaileddescription thereof, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an isometric view in partial section of a typical bootsuitable for use in the invention, the boot having a liner provided witha cavity into which the flowable fitting material is injected; and

FIG. 2 is a partially schematic diagram of one embodiment of apparatususeful in carrying out the process of the invention.

The boot shown in FIG. 1 is a typical boot of the type with which theprocess of the invention is concerned. The boot shown in this figure isdisclosed in the copending patent application filed on Jan. 7, 1972,Ser. No. 216,080, for Alden B.' Hanson and Chris A. Hanson. As describedin that patent application, the boot consists of an outer shell 10 madeof a substantially rigid plastic material which is provided with arearwardly opening tongue member 11 through which access to the interiorof the boot is obtained. The tongue member 11 is closed and heldposition by means of loops 12 which engage buckles 13 on either side ofthe boot. Into shell 10 is fitted inner padding member 14 which providesboth padding for comfort of the wearer and the capability to custom fitthe boot to the wearers foot. Inner padding member 14 has an outersurface which is generally complementary to the inside of shell 10,while the inner surface of inner padding member 14 is adapted tosurround and generally conform to the wearers foot and ankle. The rearportion of inner padding member 14, in the vicinity of tongue member 11,is cut away so as to provide access to the interior of the boot. Tonguemember 1 l is lined with a tongue liner 16 which in conjunction withinner padding member 14 essentially surrounds the foot of the wearerwith a padding layer.

Inner padding member 14 is provided with a cavity 17 in its outersurface which in conjunction with the inner surface of shell 10 definesa zone into which a flowable material can be injected in order to forceinner padding member 14 into exact conformance with the contour of thewearers foot. In a preferred embodiment, as illustrated in FIG. 1, athin bladder member 18 is shaped to fit the cavity between inner paddingmember 14 and outer shell 10. As shown in the figures, bladder 18 isshaped to extend from one side of the wearers foot over his instep tothe other side. In addition, blad der 18 is provided with a pair oftubes 19, 19a used for filling the bladder with flowable material.Although a single tube may'be used for this purpose, it is generallydesirable to use a pair of tubes, one of which is used to inject theflowable material while the other permits the escape of air.

FIG. 2 illustrates schematically one embodiment of the apparatus whichcan be used to carry out the method of the invention. It should beunderstood that the specific apparatus disclosed in this figure isillustrative only and any other apparatus having an equivalent functioncan also be used. As shown in FIG. 2, injection gun 21, filled with aflowable material which in the case of a thermoplastic substancesuitably can have a melting point within the range of about ll80F, isprovided with control valve 22 at its exit end and is attached to one ofthe filling tubes of the boot, e.g., 19. The other filling tube 19a isconnected by tube 23 to a hermetically sealed, gas pressure-tightoverflow conduit or container 24, which is also provided with pressuregauge 26 and a rubber squeeze bulb 27 equipped with bleed val-ve'28..Allof the connections between individual components are hermetically sealedso that a superatmospheric gas pressure can be built up within thesystem.

The method of the invention has as an essential element theestablishment and control ofa predetermined substantially constant backpressure on the flowable fitting material while it is being injectedinto the boot and during the solidification or final containmentthereof. As a preferred initial step in the process, the bladder elementof the boot is pressured with gas, such as air, rather than with theflowable material which is ultimately used, to a pressure level whichthe wearer of the boot agrees is comfortable while providing asufficiently snug fit for proper edge control. At this time the gaspressure is noted, and the flowable material is then injected into theboot, maintaining the predetermined back pressure until the materialhardens or is finally contained. In this way the degree-of snugnesswhich was'selected by the skier is obtained and in addition the samedegree of tightness can be obtained in each boot of a pair. With'abeginning skier, the fitter may suggest a pressure level which hebelieves to be adequate from his experience. 1

The procedure typically followed in custom fitting a pair of'ski bootsin accordance with the method of the invention is as follows. With thefoot of the wearer in place within the boot (as shown in phantom outlinein FIG. 2), control valve 22 is closed and the squeeze bulb 27 isoperated to build a superatmospheric pressure in the system consistingof bladder 18, overflow container "24 and the associated connectingtubing. The pressure which is built up within the system is measured bymeans of pressure gauge 26. Pre-pressurizing with air in this mannerserves the advantageous function of indicating to the user the degree oftightness which is created by a given pressure level. It is advantageousto produce initially a pressure which is substantially in excesspressure level has been reached. Ov'er-pressurizingin this mannerdemonstrates the effect of too tight a fit and in addition serves tostraighten out the bladder 18 within cavity 17 between the inner linerl4 and shell 10, thereby preventing the possibility of improper orincomplete filling of the bladder with fitting material.

The desired pressure level within the system having been established,control valve 22 is opened and flowable thermoplastic fitting materialis injected by means of injection gun 21 or other suitable pump meansthrough fillingtube 19 into bladder 18. The fitting mate'rial isinjected steadily while the wearer moves his foot gently within the bootuntil an overflow of fitting material issues from exit tube 19a intooverflow conduit or container 24, which is suitably transparent.Alternatively, a transparent section may be placed in tube 23 whichwould show the passage therein of excess fitting material. During theentire filling operation the air pressure is monitored on pressure gauge26 and appropriate corrections in the pressure are made by manipulatingbleed valve 28 as necessary. While the degree of back pressure isdetermined by the wearer of the boots, it will be generally found thatpressures in the range of about 0.5 to 4 psig., and particularly about1-2 psig., will be suitable for proper fitting in most cases.

As alternatives to the manual operation of bleed valve 28 duringinjection, there can also be used an automatic pressure control valveset at the desired pressure or a dip tube in a column of a suitableliquid such as mercury, water or a suitable salt solution. Althoughmercury can be used for this purpose, the health hazards which may becreated if mercury is spilled may make such use unsuitable. Water can beused, but the column necessary to create the suitable back pressuremight be inconveniehtly high (up to about 8 feet). A suitable liquid foruse in a dip-tube pressure regulating system for-this use is a solutionof zinc bromide, which can be dissolved in water to an extent of aboutby weight to give a solution having a specific gravity of about 2.7.Such a pressure-regulating system employing a solution of zinc bromideneed be only approximately 3 feet in height to cover the highest backpressure which might be used.

The use of a pressure-regulating valve or equivalent can be eliminatedentirely by making overflow conduit or container 24 large, e.g., 50-150times the volume of the bladder, or by incorporating an auxiliary volumeof such size in the system. With the desired back pressure establishedin the system at the start, injection of sufficient fitting material tofill the bladder will cause only an insignificant rise in the pressureof the system.

Although in the preferred embodiment the boot is provided with bladder18 within the cavity 17 defined by liner l4 and outer shell 10, it isalso possible to carry out the method of the invention with a boot inwhich the cavity is defined solely by the liner and the shell. In suchcase, it will be found desirable to cement the liner to the shell withparticular attention to avoiding any possible openings which wouldprevent the establishment therein of the necessary back pressure.Suitable inlet and outlet orifices to the cavity can be made in anyappropriate manner, as will be apparent to those skilled in the art.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. In the method of custom fitting a ski boot comprising an outer shell,a liner assembly disposed within said shell, said shell and said linerdefnining in part at least one cavity therebetween, which methodcomprises positioning saidboot on a foot of a person to be fitted, in-

formed of a substantially rigid material..

3. The method of claim 2, wherein there is associated with said cavity abladder member adapted to receive said fitting material.

4. The method of claim 3, wherein said back pressure is within the rangeof about 0.5 to about 4.0 psig.

5. The method of claim 3, wherein said back pressure is within the rangeof about 1-2 psig.

6. The method of claim 3, wherein said flowable material isthermoplastic and melts within the range of about l20-l80F.

7. The method of claim 3 which includes as a step preliminary toinjecting said fitting material, pressurizing said bladder with a gas toa pressure level consistent with the comfort or performance requirementsof the user, noting the pressure level, and injecting said fittingmaterial, maintaining said pressure during injection and solidificationof the fitting material.

1. IN THE METHOD OF CUSTOM FITTING A SKI BOOT COMPRISING AN OUTER SHELL,A LINER ASSEMBLY DISPOSED WITHIN SAID SHELL, SAID SHELL AND SAID LINERDEFINING IN PART AT LEAST ONE CAVITY THEREBETWEEN, WHICH METHODCOMPRISES POSITIONING SAID BOOT ON A FOOT OF A PERSON TO BE FITTED,INJECTING INTO SAID CAVITY A FLOWABLE FITTING MATERIAL, AND RETAININGSAID FITTING MATERIAL WITHIN SAID CAVITY, THE IMPROVEMENT COMPRISINGESTABLISHING WITHIN SAID CAVITY A GAS PHASE HAVING A SUPERATMOSPHERICPRESSURE, INJECTING SAID FITTING MATERIAL INTO SAID CAVITY AGAINST THEBACK PRESSURE EXERTED BY SAID GAS PHASE, AND MAINTAINING SAID BACKPRESSURE AT A PREDETERMINED SUBSTANTIALLY CONSTANT VALUE UNTIL SAIDFITTING MATERIAL IS RETAINED WITHIN SAID CAVITY.
 2. The method of claim1 wherein said outer shell is formed of a substantially rigid material.3. The method of claim 2, wherein there is associated with said cavity abladder member adapted to receive said fitting material.
 4. The methodof claim 3, wherein said back pressure is within the range of about 0.5to about 4.0 psig.
 5. The method of claim 3, wherein said back pressureis within the range of about 1-2 psig.
 6. The method of claim 3, whereinsaid flowable material is thermoplastic and melts within the range ofabout 120.degree.-180.degree.F.
 7. The method of claim 3 which includesas a step preliminary to injecting said fitting material, pressurizingsaid bladder with a gas to a pressure level consistent with the comfortor performance requirements of the user, noting the pressure level, andinjecting said fitting material, maintaining said pressure duringinjection and solidification of the fitting material.